Combined air cycle heat pump and refrigeration system

Abstract

In an air conditioning system for a load, air is used as the refrigerant, and identical components including a turbocompressor and a regenerative heat exchanger are used for both cooling in the refrigeration mode and heating in the heat pump mode. A plurality of valves are arranged so that in the refrigeration mode the refrigerant air operates in a closed dry air loop to avoid problems associated with moisture. In the heat pump mode the valves are arranged to cause the refrigerant air to operate open loop by using ambient air as the input to the cycle, and avoiding icing problems by rejecting the refrigerant air, together with any ice present, back into the ambient. Operation closed loop in the refrigeration mode and open loop in the heat pump mode results in maximum cycle efficiency with minimum difficulty caused by moisture entrained in the refrigerant air.

I claim: 
     
       1. A combined air cycle heat pump and refrigeration system for a load comprising: a source of low pressure refrigerant air at essentially ambient pressure, said refrigerant air being ambient air when said system is operating in the heat pump mode and being air returned from said load when said system is operating in the refrigeration mode;   a turbine driven compressor receiving said refrigerant air and increasing the temperature and pressure thereof;   means for conducting said compressed refrigerant air to said turbine for expansion therein and discharge therefrom whereby said refrigerant air is reduced in temperature;   means for conducting the refrigerant air discharged from said turbine directly to the ambient when said system is operating in the heat pump mode, and for conducting the refrigerant air discharged from said turbine directly to said load when said system is operating in the refrigeration mode;   a regenerative heat exchanger connecting through heat transfer surfaces within said regenerative heat exchanger the source of low pressure refrigerant air with the compressed refrigerant air upstream of said turbine whereby said compressed refrigerant air rejects some of its heat to said low pressure refrigerant air from said source and reduces the temperature of the compressed refrigerant air fed to said turbine so as to maximize the reduction in the temperature of the refrigerant air discharged from said turbine;   additional heat exchange means downstream of said compressor and upstream of said regenerative heat exchanger on the high pressure side thereof, said compressed refrigerant air passing through said additional heat exchange means;   an additional fluid, said fluid being fluid returned from said load when said system is operating in the heat pump mode and said fluid being ambient air when said system is operating in the refrigeration mode;   means for passing said fluid through said additional heat exchange means in heat exchange relation with said compressed refrigerant air whereby said fluid absorbs heat from said compressed refrigerant air;   and means for returning said fluid to supply heat to said load when said system is operating in the heat pump mode and returning said fluid to ambient when said system is operating in the refrigeration mode.   
     
     
       2. A combined air cycle heat pump and refrigeration system as in claim 1 and including a plurality of two-way fluid valves connected with said low pressure refrigerant air source, with said turbine discharge air path and with said additional fluid path, said fluid valves being adapted to maintain said system in the heat pump mode in one position, and to maintain said system in the refrigeration mode in the other position. 
     
     
       3. A system as in claim 1 in which said additional load fluid is air. 
     
     
       4. A system as in claim 1 in which said additional load fluid is a liquid. 
     
     
       5. A system as in claim 1 and including electric motor means having coils for supplying additional torque to said compressor: and means for passing the refrigerant air from said compressor through said motor coils to cool said coils and provide additional heat to said refrigerant air.   
     
     
       6. A heat pump system as in claim 1 and including solar heating means in the path between said source of ambient refrigerant air and said regenerative heat exchanger for providing additional heating to said ambient refrigerant air. 
     
     
       7. A system as in claim 1 and including means connected with said regenerative heat exchanger for removing moisture therefrom. 
     
     
       8. A combined air cycle heat pump and refrigeration system comprising: a source of refrigerant air;   a regenerative heat exchanger having low pressure fluid passage means and high pressure fluid passage means in heat exchange relation;   means for passing said refrigerant air through the low pressure fluid passage means of said regenerative heat exchanger;   a compressor;   a turbine for providing torque to said compressor;   motor means for providing additional torque to said compressor;   means for passing said refrigerant air from the low pressure fluid passage means of said regenerative heat exchanger to said compressor, said compressor raising said refrigerant air in pressure and temperature;   additional heat exchange means receiving said compressed refrigerant air whereby some of the heat in said compressed refrigerant air is rejected to a fluid passed through said additional heat exchange means and in heat exchange relationship with said compressed refrigerant air;   means passing said compressed refrigerant air from said additional heat exchange means to the high pressure fluid passage means of said regenerative heat exchanger where additional heat from said compressed refrigerant air is rejected to the refrigerant air passed through the said low pressure fluid passage means of said regenerative heat exchanger;   and means for expanding the refrigerant air passed through the high pressure fluid passage means of said regenerative heat exchanger in said turbine.   
     
     
       9. A method for selectively heating and cooling a load utilizing an air cycle comprising the steps of: providing a first source of air from said load and returning said load air to said load;   providing a second source of ambient air and returning said ambient air to ambient;   selecting one of said first or second air sources as refrigerant air, said first air source being selected when it is desired to cool said load and said second air source being selected when it is desired to heat said load;   compressing said refrigerant air to increase the pressure and temperature thereof;   expanding said compressed refrigerant air in a turbine and discharging said refrigerant air therefrom;   connecting through heat transfer surfaces within a regenerative heat exchanger the source of refrigerant air with the compressed refrigerant air upstream of said turbine whereby said compressed refrigerant air rejects some of its heat to said refrigerant air from said source, thereby reducing the temperature of the compressed refrigerant air expanded in said turbine so as to maximize the reduction in temperature of air discharged from said turbine;   and connecting through heat transfer surfaces within an additional heat exchanger located upstream of said regenerative heat exchanger and compressed refrigerant air with the other of said first or second air sources whereby said compressed refrigerant air rejects heat to said other air source.   
     
     
       10. In an air cycle refrigeration machine using ambient air as the refrigerant air and operating as a heat pump to supply heat to a load; a turbine driven compressor receiving said refrigerant ambient air and increasing the temperature and pressure thereof;   a first heat exchanger downstream from said compressor;   means for circulating a fluid from said load through said first heat exchanger and returning said fluid to said load;   means connecting said compressed refrigerant air from said compressor through heat transfer surfaces in said first heat exchanger with said fluid whereby said compressed refrigerant air rejects heat to said fluid, said heated fluid being used to provide heat to said load;   a regenerative heat exchanger downstream from said first heat exchanger and connecting through heat transfer surfaces within said regenerative heat exchanger the ambient air used as the refrigerant air with the pressurized refrigerant air from said first heat exchanger whereby said pressurized refrigerant air rejects some of its heat to said ambient air and reduces the temperature of said pressurized refrigerant air to as close to ambient as possible;   and means for conducting said pressurized refrigerant air from said regenerative heat exchanger to said turbine for expansion therein, said turbine cooling said refrigerant air and discharging said cooled refrigerant air to ambient at a temperature as far below ambient as possible.   
     
     
       11. In an air cycle refrigeration machine using a source of air from a load as the refrigerant and operating as a refrigeration machine to cool said load; a turbine driven compressor receiving said refrigerant air from said load and increasing the pressure and temperature thereof;   a first heat exchanger downstream from said compressor;   means for providing a source of ambient air to said first heat exchanger and discharging said ambient air to ambient;   means connecting said compressed refrigerant air from said compressor through heat transfer surfaces within said heat exchanger with said ambient air whereby said compressed refrigerant air rejects heat to said ambient air;   a regenerative heat exchanger downstream from said first heat exchanger and connecting through heat transfer surfaces within said regenerative heat exchanger the source of refrigerant air from said load with the pressurized refrigerant air from said first heat exchanger whereby said pressurized refrigerant air rejects some of its heat to said refrigerant air from said load and reduces the temperature of said pressurized refrigerant air to as close to the refrigerant air temperature from said load as possible;   and means for conducting said pressurized refrigerant air from said regenerative heat exchanger to said turbine for expansion therein, the turbine discharge air being conducted to said load to cool said load, said turbine discharge air being as far below load temperature as possible.